I don't know if this works prior to 3.1.x but this works here:
You set or get the value or string you want to display with e.g. Env variables. To insert them you can use backticks.
Edit:
using backticks (3.0+ i think)
LIST `REQUESTFILE DRAWERSONLY'
Example 1
SETENV myval "important"
REQUESTCHOICE TITLE "hello user" BODY `GETENV myval` OkeyDokey
Example 2
You can also use a script as a body for the requester( the variable acts as a script).
Edit: ok, maybe not full scripts, but internal cmds, like ECHO, EVAL etc.
SETENV myval "ECHO 42"
REQUESTCHOICE TITLE "hello user" BODY `$myval` OkeyDokey
Hint
SETENV F 5
SETENV S 6
EVAL $F+$S
EVAL $F*$S
Example 3
And, finally, if you shape your myval with additional words separated with spaces, those become gadgets as well
SETENV myval "important Okey"
REQUESTCHOICE TITLE "hello user" BODY `GETENV myval` Dokey
As you already 'captured' your variable, just insert that instead.
Or, as Example 4
C:DATE >ENV:myval
REQUESTCHOICE TITLE "hello user" BODY "`GETENV myval`" "Okey Dokey!"
As Date outputs a string with spaces you certainly like to surround it with " ".